One female victim was in critical condition, while two male victims suffered minor injuries, according to the San Francisco Police Department. The female victim may have been targeted they said, adding that the incident was “not a random shooting.”

The victims ran into the school after they were shot, police said, and four male suspects in dark jeans and hoodies were seen running away. Police weren’t aware whether they were students, and no one has been taken into custody.

Nearly three hours after San Francisco Police first announced the incident, it tweeted, “A 4th victim walked into #SanFranciscoGeneral Hospital with non-life threatening injuries related to this incident.”

No further information about the nature or cause of the injury was provided.